At the present time, petroleum or natural gas is used as the starting material in the commercial production of carbon black. It is well known that carbon black can be produced from carbonaceous material, such as coal. Such patents as U.S. Pat. Nos. 3,424,556, Johnson, and 3,975,504, Cheng, disclose processes for producing carbon black from coal.
Commercially acceptable carbon black, however, has not been produced from coal or other carbonaceous material because of the high ash content of the resultant product, and the extreme difficulty and expense in attempting to separate the ash from the carbon black, although otherwise the economics would be favorable to such a process if the ash content could be reduced.
In producing carbon black from coal in accordance with the processes of the prior art, ash is also produced and the separation process is extremely difficult so that it is not feasible to make carbon black with an ash content of less than one percent, which constitutes the commercially acceptable standard.